In Vitro Dry Matter Digestibility, Gas Production And Ph Of Silages Of Several Maize Hybrids

Abstract The objective of this study was to determine the in vitro dry matter digestibility (IVDMD), gas production and pH of silages of 10 maize hybrids in Iturama, Brazil (XB 6012 BT, BM 709 VT PRO2, BM 815 VT PRO2, DKB 363 VT PRO3, AG 8740 VT PRO3, SYN 555 VIP3, SX 8555 VIP3, SX 7005 VIP3, DKB 390 VT PRO3, and RB 9789 VIP3). The maize was ensiled in experimental mini silos in a completely randomized design with 3 repetitions. After 120 d, a subsample from each mini silo was taken and the IVDMD was estimated using Ankom Daisy II and F-57 bags (n = 44). Rumen fluid from two cannulated Nellore steers were mixed and placed into fermenter jars containing Ankom buffers (1:4; v/v). After 48-h incubation (39ºC), 40 mL 6 N HCl and 8 g pepsin were added to each jar and incubated for another 24 h. For gas production and pH evaluations, penicillin-type glass vials (n = 40) were filled with McDougall buffer (20 mL), rumen fluid (10 mL) and substrates (200 mg) and incubated in a shaker (39ºC) for 24 h. The cumulative pressure was measured, vials were opened, and terminal pH was measured. Data were analyzed using the MIXED procedure of SAS. The DKB 363 VT PRO3 presented the greatest IVDMD (84.9%, P = 0.02) and the lowest pH (6.60, P = 0.002). The opposite was observed for DKB 390 VT PRO3, which presented the lowest IVDMD (71.1%) and the greatest pH (6.65). The BM 709 PRO2 produced more gas than the others (246.1 mL/g DM), while SYN 555 VIP3 produced less gas than the others (167.7 mL/g DM, P = 0.0005). In conclusion, the material DKB 363 VT PRO3 presented the most interesting characteristics for use as silage for beef cattle in Iturama, Brazil.